The term colour fastness refers to two resistance criteria of a colour of a test sample. The first criterion is the resistance of a material to change in any of its colour characteristics. The second criterion is the resistance of its colourant(s) to adjacent materials as a result of exposure of the material to any environment that might be encountered during the use of the material.


The first resistance criterion is checked by the “rubbing fastness” test. The term “rubbing fastness” is the term for the hue change of the test sample through rubbing. This test is evaluated visually with a comparative scale. Most common is the use of a “gray scale for staining”.


“Crocking” and “smudging” are both equivalent terms for the transfer of colorant(s) from the test surface to another surface or to an adjacent area by rubbing. Therefore, if the second resistance criteria is checked, you test the crock resistance (equally called smudge resistance).

 

Abrasion resistance is the ability to withstand the frictional forces attempting to remove the surface material.

When testing the solvent resistance of a surface it is checked how much of the coating remains after a defined number of double strokes.

At the washability / cleanability test procedure you check if a coating can be cleaned with a standardized procedure without removing more than a defined film thickness after a defined soiling.

Constant and defined film thicknesses is a precondition for testing and analysis of coating materials and coatings. Many properties of these materials depend on the film thickness.

It is important to know that for physical reasons the maximum achievable wet film thickness is not equal to the gap height. The following guidelines apply:

Gap heightWet film thickness
15 - 100 µm (0.59 - 3.94 mil) about 50 %
above 100 - 300 µm (3.94 - 11.81 mil) about 60 %
above 300 - 500 µm (11.81 - 19.69 mil) about 80 %
above 500 µm (19.69 mil) up to 90 %


For the choice of the correct gap height please also consider that the dry film thickness obtained can be less than the wet film thickness depending on the weight percent of solids.

There are wedge-shaped and uniform applications. For wedge-shaped applications, we offer the ZUA 2000 and ZUA 2002 Universal Applicator. There is a wide choice of uniform applicators from wire-bar, profiled, semi-circular, 4-sided up to universal applicators.

 

Flexibility / elongation is the pliability or rigidity of a material. It expresses the extent to which it resists bending. There are several empirical test procedures for assessing the resistance of a coating of paint, varnish or related product to cracking and/or detachment from a metal or plastic substrate. There are the bend test, the impact test and the cupping test.

Bend test

Mandrel testers are common test apparatuses used for the determination of the elongation/and adhesion of coatings at bending stress. At a bend test a test panel is bend over a certain radius.

Conical mandrel testers bend the test panels over a conus so that a large variety of bending radii is tested at the same time.

The cylindrical mandrel test can be carried out as a quick pass/fail test with a single mandrel of specified diameter or as repeated procedure with decreasing mandrel diameters for determining the diameter of the first mandrel causing failure.

Impact test

Impact tests are a test method for evaluating the resistance of a dry film of paint, varnish or related product to cracking or peeling from a substrate when it is subjected to a deformation caused by a falling weight dropped under standard conditions.

 

The density is an essential quality characteristic, for example it allows recognising errors regarding the composition and gives indications of the purity of a product.

The test principle is based on the weighing of a given volume of the liquid under test, as it is defined by the pycnometer. From the difference of the masses of the filled and the empty pycnometer as well as the known filling volume the density is calculated. The density p in g/ml at the test temperature t can be calculated using the following equation:

    p = (m2 - m1) / Vt

p = density in g/ml of the sample at the test temperature t
m1 = mass in g of empty pycnometer
m2 = mass in g of probe filled pycnometer at the test temperature t
Vt = volume of the pycnometer in ml at the test temperature t

The result is not corrected for air buoyancy because the uncorrected value is required by most filling-machine control procedures and the correction (0.0012 g/ml) is negligible in relation to the precision of the method.

 

The cross-cut test is a very rapid and simple method for the assessment of single and multi-coat systems. Here, cuts in a 30° angle (method A) or right-angle (method B) are executed so that you receive a lattice pattern or an X-shape. These test methods can be used as quick pass/fail tests. When applied to a multi-coat system, assessment of the adhesion of individual layers of the coating among each other may be carried out.

Choice of the appropriate cross-cut method

  • Methode A (X-cut) for tests in accordance with ASTM D 3359 with thickness > 125 µm (4.92 mil)
  • Methode B (lattice pattern) for tests in accordance with ISO 2409 with thickness 0 - 250 µm (0 - 2.36 mil) and ASTM D 3359 with thickness <125 µm (4.92 mil)


Choice of the appropriate spacing of cuts (method B) in accordance with ISO 2409:

Film thicknessSubstrateSpacing of cuts
0 to 60 µm (0 to 2.36 mil) hard 1 mm (0.04“)
0 to 60 µm (0 to 2.36 mil) soft 2 mm (0.08“)
over 60 to 120 µm hard or soft 2 mm (0.08“)
over 60 to 250 µm (2.36 to 4.72 mil) hard or soft 3 mm (0.12“)


Choice of the appropriate spacing of cuts (method B) in accordance with ASTM D 3359:

Film thicknessSpacing of cuts
0 to 50 µm (0 to 2.0 mil) 1 mm (0.04“)
50 to 125 µm (2.0 to 5 mil) 2 mm (0.08“)

 

Gloss is an opti­cal pro­per­ty of a sur­face, cha­racter­ized by its ability to re­flect light. If a light beam strikes a sur­face - e.g. a lacquer - with a cer­tain angle of inci­dence (ε), most of it will pene­trate the layer of paint, the rest will be re­flec­ted.

Usually, the measuring results for paints and varnishes are indicated between 0 and 100 gloss units. It is important to remember that this number is not a value in percentage. The reflectometer value is not related to the amount of light but to a black polished glass standard of a defined refractive index (1,567). For this standard, the measured value is set to 100 gloss units (GU).

Polished metals, mirrors and certain foils have a much higher refractive index than varnishes and as the black glass standard used for calibration. For this reason, you may find much higher gloss values than 100 for these products, in fact up to 2‘000 GU.

 

This test is valid for flat road markings and road markings with low degree of texture. Road markings with high degree of texture or structured markings may not be suitable for measurement of skid resistance by this method.

 

The adhesion of a coating on a substrate is crucial for the mechanical performance as well as for the corrosion protection. In practice, there are several test procedures for determining the adhesion such as cross-cut test, mandrel test and impact test.

Cross-cut test

The cross-cut test is a very rapid and simple method for the assessment of single and multi-coat systems. Here, cuts in a 30° angle (method A) or right-angle (method B) are executed so that you receive a lattice pattern or an X-shape. These test methods can be used as quick pass/fail tests. When applied to a multi-coat system, assessment of the adhesion of individual layers of the coating among each other may be carried out.

Bend test

Mandrel testers are common test apparatuses used for the determination of the elongation/and adhesion of coatings at bending stress. At a bend test a test panel is bend over a certain radius.

Conical mandrel testers bend the test panels over a conus so that a large variety of bending radii is tested at the same time.

The cylindrical mandrel test can be carried out as a quick pass/fail test with a single mandrel of specified diameter or as repeated procedure with decreasing mandrel diameters for determining the diameter of the first mandrel causing failure.

Impact test

Impact tests are a test method for evaluating the resistance of a dry film of paint, varnish or related product to cracking or peeling from a substrate when it is subjected to a deformation caused by a falling weight dropped under standard conditions.

 

Many standards describe corrosion tests where a coating has to be prepared with scratch marks that penetrate it completely down to the metal substrate. Possible instruments are scratching tools according to Sikkens or Clemen and Cross-cut testers.

 

The degree of chalking, a measure for the amount of particles exposed by chalking, is determined by the reduction in the intensity of light passing through the adhesive tape after having applied to the coating.

Chalking is the appearance of a loosely adherent fine powder on the surface of a paint coating arising from the degradation of one or more of its constituents (EN DIN ISO 4628).

The chalking tester which measures the chalking resulting from natural or artificial weathering of coatings is based on the analytical principle of nephelometry and the adhesive tape method according to Helmen.

 

The fineness of grind is particularly important during the manufacture of pigmented products. By its determination the efficiency of dispersion processes can be followed, and the performance of dispersion apparatuses and methods can be determined.

 

Measures the coefficient of retroreflected luminance (night visibility) of road markings. The observation angle of 2,29° corresponds to the viewing distance of a vehicle driver of
30 m under normal conditions. The illumination angle is 1,24°.

Night visibility RL

Retroreflection value R of road studs

A raised pavement marker is a safety device used on roads. These devices are usually made with plastic, ceramic, or occasionally metal, and come in a variety of shapes and colors. Many varieties include a lens or sheeting that enhance their visibility by reflecting automotive headlights. Road studs might be damaged due to high speed and snow plugs. Road studs increase the visibility of road markings.

Coefficient of retroreflection RA of traffic signs

Performance limits to the coefficient of retroreflection RA of traffic signs are defined within international standards. A traffic sign with a high visibility attribute has a big importance because it improves the safety on the road.

Coefficient of retroreflection R‘ of safety garments and contour safety markings

Performance limits to the coefficient of retroreflection R‘ of safety garments and contour safety markings are defined within international standards. High-visibility clothing has highly reflective properties mostly be retroreflective stripes. Yellow waistcoats are a common example.

 

The roughness of a surface can be defined by it's macro texture. Horizontal drainability is the capacity of the road surface to provide interconnecting voids through which water can be squeezed out by a moving tyre.

 

The visibility is an important factor for road markings, traffic signs, road studs as well as high-visibility material such as warning clothes and Heavy good vehicles (HGV's) contour safety marking.

Retroreflection of road markings is obtained by glass beads which protrude from the road marking and depends on different conditions for example:

  • degree of embedding / size
  • quantity
  • quality


A road marking with a high visibility attribute has a big importance because it improves the safety on the road. By decreasing accidents the consequental costs can be recuded.

There are different methos to determine the visibility of road markings:

  • Night visibility RL (coefficient of retroreflected luminance)
  • Day visibility Qd (luminance coefficient under diffuse illumination)
  • Luminance factor ß

 

For cost and quality reasons the determination of both, the wet and dry thickness has become more important during the last years.

Wet film thickness

For several reasons it is important to determine the thickness of freshly applied liquid (”wet”) coatings: The applied film thickness is often decisive for the quality of the coated product. On the other hand, the quantity of applied material should not be too high, both for technical and economical reasons.

Dry film thickness

For several reasons it is important to determine the dry thickness of coatings: Many coating properties such as adhesion and hardness depend on the dry film thickness. The measurement methods for measurements of dry film thickness can be classified as destructive and non destructive.

Destructive dry film thickness determination

The destructive wedge cut method is particularly important for determining the dry film thickness on substrates such as wood, concrete, plastic and other non magnetic substrates. On these substrates most of the conventional non destructive electro-magnetic methods cannot be used.

Non-destructive dry film thickness determination

Zehntner offers two dry film thickness gauges for checking or measuring the dry film thickness of road markings.

 

Zehntner develops their own software for meeting and exceeding customer requirements. This starts with firmware to Zehntner products, an extra measuring and data analysis software up to an independent software such as the Zehntner App.

 

The day visibility is a method to assess road markings. It measures the luminance coefficient under diffuse illumination (day visibility) of road markings. The observation angle of 2,29° corresponds to the viewing distance of a vehicle driver of 30 m under normal conditions. The illumination must be diffused light.

Day visibility Qd

 

Drying properties, shrinking, mud-crack, cracking and porosity are important characteristics which should be tested during the manufacture of coating materials and fillers. By using drying gauges, reliable product data can be determined by which disagreeable surprises at the users side will be spared. The no-pick-up time is the drying time required for no-pick-up by the tire of an automobile.

 

An important property of liquids is their viscosity. A measure for the viscosity is the flow time, determined at a specifi ed temperature, using a flow cup.

 

Hardness testing is an easy and fast method to determine the force needed to scratch a surface. The hardness degree of a surface is jointly responsible for the scratch hardness especially when scratching of sharp-edged articles or materials.

 

 The visibility of road markings is a cru­cial fac­tor in ensur­ing traffic safety. Hence it is inevit­able that road mark­ings are checked, main­tained and if neces­sary re­placed on a regular basis.